Safety device for elevators or lifts



w. R.-PABlcH SAFETY DEVICE FOR ELEVATORS 0R LI-FTS Filed Dec. 14. 1944 INVENTOR. ZUQZZ QIJZ P626 4 Patented Oct. 14, 31947 UNITED STATES PATENT OFFICE SAFE TY "DEVICE FOR EIJEVATQRS OR DIFTS Walter R. ranch, -.Chicago 111. Application December 14, 1'944,"Serial 'No. 56851 30 .6 Claims.

1 The present invention relates generally to an elevator platform for elevating material such as sheet or box blank forms adjacent an operating machine for conveniently feeding the topmost sheet or box blank into the machine, but more particularly to a safety device which will prevent the accidental drop of the platform-due to failure of the power or the breakage of some operating parts.

One of the primary objects of the present invention is to provide a simple, improved safety device for a material elevating platform which will prevent the accidental drop of the platform and prevent injury to the operator should breakage occur in the operating parts of the-elevating mechanism or for any other reason.

A further objectof the invention is to provide .a novel and improved construction of safety'device for an elevating platform to prevent the accidental droppin of the platform and so ar- -1- ranged with respect to the control for lowering :the platform that the safety device is rendered inoperative to permit the elevating platform to be lowered to its lowermost position.

These and other objects are accomplished by providing'a construction and an arrangement of the various parts in the manner hereinafter describedand particularly pointed out in the apfpended claims.

Referring to the drawings:

Fig. 1 is a side elevational view ofa fragmenitary portion of an elevating mechanism and plat- ;form having my improved safety device'embodied therein; and

Fig. 2 is asimilarffront elevational view-of the device shown in Fig. 1.

In illustrating one adaptation of my improved safety device, I have shown the same in connection with an automatic lift or elevator andcontrols therefor, a fragmentary portion of which is shown in Fig. 1 of the drawings. The automatic lift or elevator is of the hydraulic type and a detailed description of theconstruction and operation is clearly disclosed in my co-pending application, Serial No. 563,222, filed November 13, .1944.

The automatic lift or elevator to which my improved safety device is attached comprises briefly; opposite side and main frame members ill in which are vertically and adjustably mounted by means of "guide rollers ll, an form, generally indicated by the reference character l2. Mounted on the platform l2 are a, pile of sheets or box blanks, generally indicated by the reference character I3.

The hydraulic mechanism for hoisting the platelevating plat- ;of the shaft 2'! is ahand :form comprises :briefiy a .pump housing generally indicated by the reference character M, which icontainsa .pump (not shown). Communicating with the opposite ends of the pump housing are conduits 5|5and l6, which in turn, are connected -to anld .communicate with a .hydraulic motor, gen- ?erally indicated :by-.the reference character ll. Connectedbetween themotorll and the conduit A6 is .a ;controlxval've :generally indicated by the reference character [3. The fluid motor I1 is adaptedto actuate a piston 19, which in turn, throughesseriessof :pulleys 20, 2|, 22 and cables .253 provides the power to intermittently lift the platform l2 in the manner described in my aforementionediapplication. The valve I8 is provided witha crank-arm 24 which has itsouter end con- :nected to the lower'end of a rod or bar 25. The upper end of the bar 25 is'pivotally connected'to the outer end of a crank 26, which in turn, is secured to a'transver-se shaft 21. The opposite ends of the shaft '21 are journaled in suitable hearings carried by the side frame members [0 of the elevator frame. Secured adjacent one end operated crank or lever .28, whichmay be actuated in a direction indicated byzthe arrow in Fig. 1 to lower the platform. The elevating mechanism and hydraulic power lift therefonis identically like and functions in the same manner as that disclosed in .myaforementioned application and therefore, a detailed description'of the function and operation may-be had by reference to this-prior application.

'My :improved safety device for preventing the accidental :dropping of the elevator platform, comprises a vertically extending rack bar 29 which issecured to the forward edge to one of the main 'frame members In by means of bolts 30. The :forwardedge of 'thisbar is provided with a plurality of vertically spaced recesses or notches 3| forming in-effect ratchetteeth, anyone of which 'is'adapted'to'be engaged by a pawl 32. The pawl "32 is pivoted-on a pin or bolt 33, which in turn, is secured to the outside surface of an extension 34, of one of 'the frame members of the platform [2. The pawl 32 is normally pressed'into'engagement with any one of the recesses 3! of the bar 29 by a spring generally indicated by the reference character 35, which in turn is carried by the eX- tension 34 at --a point adjacent thepawl 32. In

'order to'hold the pawl 32 out of engagement with he teethwhen the platform is being lowered for a new supply of box blanks, a vertically extending and diagonally movable guide bar 36 is positioned adjacent the rack bar 29 and on one side thereof. This rack bar 29 is adapted to be moved into the path of the pointed portion of the pawl 32 so as to disengage the same from the teeth of the rack bar 29. The guide bar 36 is provided with diagonally or inclined slots 31 which are located adjacent the upper and lower ends thereof. Extending through each of these slots 31 are guide posts or pins 33 which are secured to the bar 29. Pivotally connected to the upper end of the bar 36 as shown at 39 is a link 40. The upper end of the link 49 is pivotally connected as shown at Al to a crank arm 42, which in turn is secured to the shaft 21 adjacent the lever 28.

Summarizing the advantages and function of operation of myimproved safety device, it will be observed that when the hand operating lever 28 is actuated in a direction indicated by the arrow in Fig. l of the drawings, the crank 26 on the shaft 21 will be actuated in the same direction, thereby actuating the connecting link 25 and open the valve It to lower the platform l2. Simultaneousiy with the movement of the lever 28, the bar 36, through the crank 42 and link 40, will be actuated downwardly and outwardly with respect to the bar 29, by reason of the inclined slot 31 and guiding bolts 38. As the guide bar 36 is moved downwardly and outwardly, it will disengage the pawl 32 from the rack bar 29 and hold the same disengaged while the platform i2 is lowered to its lowermost position. Upon return of the crank 28 to the vertical position, the pawl 32 will then be free to engage the notches 3| in the rack bar 29 andthereby prevent the accidental dropping of the platform 23 during its normal operation.

While in the above specification I have described one embodiment which my invention may assume in practice, it will of course be understood that the same is capable of modification and that modification may be made without departing from the spirit and scope of the invention as expressed in the following claims.

What I claim as my invention and desire to secure by LettersPatent is:

1. In a lift device of the character described, the combination of a frame, a lift platform mounted on said frame, power lift mechanism mounted on said frame for lifting said platform, a lever for controlling said mechanism, a safety device for said platform, mounted on said frame and including a rack bar, a pawl carried by said platform and engageable with said rack, and means movable into the path of said pawl and operatively connected to said lever for synchronizing said lift mechanism with said safety device.

2. In a lift device of the character described, the combination of a guide frame, a lift platform mounted on said frame, power lift mechanism mounted on said frame for lifting said platform, a lever for controlling said mechanism, a safety device for said platform including a rack bar mounted on said frame, a pawl carried by said platform and engageable with said rack, a guide bar movably supported on said rack bar and adapted to move into the path of said pawl and operative connections between said guide bar and said lever for synchronizing the operation of said power lift mechanism and said safety device;

I 3. In a lift device of the character described, the combination of a frame, a lift platform mounted on said frame, power lift mechanism for lifting said platform, a lever for controlling said mechanism, a safety device for said platform, including a rack bar secured to one side of said frame, a spring pressed pawl pivotally supported on said platform and adapted to engage said rack bar, an angularly movable guide bar carried by said rack bar and movable into the path of said pawl for disengaging said pawl from said rack bar, and a link forming part of the connections between said guide bar and said lever for synchronizing the operation of said power lift mechanism and said safety device.

i. In a lift device of the character described, the combination of a frame, a lift platform mounted on said frame, a power lift mechanism for lifting said platform, a shaft mounted on said lift device, a hand operating lever secured to said shaft, operative connections between said shaft and said power lift mechanism for controlling said power lift, a safety device including a rack bar secured to said frame, a spring actuated pawl carried by said platform and engageable with said rack bar, a guide bar positioned adjacent said rack bar and movable into the path of said pawl for disengaging said pawl from said rack bar, a crank arm secured to said shaft, and a link connecting said crank arm with said guide bar whereby said power lift mechanism and said safety device are synchronously controlled by the operation of said lever.

5. In a lift device of the character described, the combination of a frame, a lift platform mounted on said frame, a hydraulic motor for lifting said platform, a valve associated with said motor for releasing the fluid pressure in said motor 0 lower said platform, a lever mounted on said lift device and operatively connected to said valve, a rack bar secured to said frame, a spring pressed pawl carried by said platform and normally engaging said rack bar, a gui e bar positioned adjacent said rack bar and movable into the path of said pawl for disengaging said pawl from said rack bar, and operative connections between said guide bar and said lever whereby the pawl is disengaged from said rack bar simultaneously with the actuation of said valve to lower said platform.

6. In a lift device of the class described, the combination of a frame, a lift platform mounted on said frame, a fluid pressure motor for lifting said platform, means including a lever for controlling said motor to lower said platform, a pawl and rack mechanism positioned between said platform and said frame, a pawl engaging member positioned adjacent said rack, and operative connections between said pawl engaging member and said lever for withdrawing said pawl from engagement with said rack simultaneously with the lowering of said platform.

WALTER R. PABICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 143,013 Hubbard Sept. 23, 1873 470,960 Tracy Mar. 15, 1892 806,745 Le Fevre Dec. 5, 1905 

